The amplifier circuit radio circuit of the radio frequency mixer and containing radio

 

The invention relates to a structure oriented on the radio, in particular, to the structure of the CMOS circuits for digital radio transceiver. The proposed amplifier circuit of the radio receiver, implemented on the basis of a CMOS chip comprising two channel unipolar field-effect transistor (CPU-effect transistor) with a common gate and two input CPU-effect transistor with a standard threshold voltage, which is fed the input signal, and the input of the CPU transistors connected to the supply voltage and ground, and the CPU transistors with a common gate connected in a cascade configuration between the input of the CPU-transistors, while the CPU transistors with a common gate have a reduced threshold voltage in comparison with a standard threshold voltage input of the CPU transistors. Also the proposed scheme RF mixer containing two transmission gate, each of which includes two CPU transistor, and the corresponding signals of the local oscillator are fed to the gates of the transistors, and the input signal applied to the inputs of transmission gates, the transistors of the transfer gates have a reduced threshold voltage than transistors having radioparent implemented on the basis of these CMOS-chip amplifier and mixer. The result is improved efficiency of operation of CMOS circuits at low supply voltages. 3 S. and 1 C. p. F.-ly, 4 Il.

The technical field This invention relates to a structure oriented to radio communications, in particular to the structure of the CMOS (complementary metal oxide semiconductor) CMOS for digital radio transceiver.

The prior art In the field of digital mobile telephone to transmit and receive radio signals, which contain digital signals. In addition, in the preferred embodiment, the mobile communication transceiver must be small and light as possible, and to have low power consumption. It is advisable to implement the digital components of the transceiver, such as a digital signal processor, analog-to-digital Converter (ADC) and digital-to-analogue Converter (DAC) using CMOS technology. This means that from the point of view of manufacturing is also advisable to implement analog transceiver components, such as amplifiers, mixers, etc. using the same CMOS fabrication technologies. The structure of this type is disclosed in for Spread-Spectrum Communications"), C. Sheng (S. Sheng and others, international conference on solid state circuits (International Solid-State Circuits Conference, 1996.

However, CMOS transistors are typically intended for functioning as switches with low leakage currents. The consequence of this is that these transistors are less suitable for use in analog RF circuits. For example, they typically have low values of slope, especially at low bias voltages, resulting in low gain and high (phase) noise.

In U.S. patent 5407849 disclosed a method of manufacturing a CMOS in which the threshold voltage of some of the transistors (field-effect transistors (FETS)) reduce, for example, so that it is close to zero volts.

Brief description of the invention Thus, if the implementation of all schemes decided to use CMOS technology, the structure for communication prior art requires compromise the functioning of the device. Meanwhile, in U.S. patent 5407849 disclosed a method of reducing the threshold voltage of some field-effect transistors in the circuit with CMOS, but not revealed how it can be used in the design for the radio.

The invention includes circuitry for digital radio.

In a preferred embodiment, the invention includes the use of transistors with high or normal threshold voltages in circuits that process digital signals, and transistors with reduced threshold voltages in circuits that process analog signals.

In addition, the invention may also include the use of circuits in the input stage of a radio transceiver of a number of transistors with high or normal threshold voltages and a number of transistors with reduced threshold voltages. Such a transceiver may be a CMOS device, or it can be used only n-MOS (MOS-structure with a channel of n-type (NMOS) or p-MOS (MOS-structure with a channel of p-type (PMOS) device.

A brief description of the drawings Fig. 1 is a fundamental block diagram of a radio transceiver in accordance with the invention.

Fig. 2 is a schematic diagram of the input stage in accordance with the invention.

In Fig. 3 shows a first conventional scheme, explaining the advantages of the present invention.

In Fig. 4 until the of Ianto implementation As shown in Fig. 1, the radio transceiver 2, used in telephone apparatus, mobile communication, has a receiving antenna 4 for receiving radio signals and a low noise amplifier 6 to restore the received signal to usable levels. Amplified signals are sent to the mixer 8, where they perform the transformation frequency from high to a lower intermediate frequency, and then filtered in the filter 10. The filtered signals are in analog-to-digital Converter (ADC) 12, which converts the signals into a digital form in which they can be processed by the processor 14 of the signal, after which exercise their output on line 16.

Signals for transmission serves in digital form on line 18 in the processor 14 of the signal, and then after processing serves to analog Converter (DAC) 20. After conversion to analog form the signals are passed to the modulator 22 for conversion into a high frequency, and then - in amplifier 24 power and transmitting antenna 26 (which may be combined with the receiving antenna 4) for transmission as a radio signal.

The General structure of the transceiver described in General terms above, known to a person skilled in the art, and it is obvious that who is denite circuit in a single chip.

The authors of the present invention here, it was recognized that the transceiver shown in Fig. 1, includes diagrams of two different types, which have different requirements, and that these contradictory requirements can be met by using different schema types of transistors with different threshold voltages. This allows you to optimize the characteristics of the transceiver, providing, however, can generate radiochem in a single monolithic integrated circuit, which has advantages from the point of view of size and weight of the phone.

In particular, digital components, such as analog-to-digital Converter (ADC) and digital-to-analogue Converter (DAC) in the preferred embodiment is formed using CMOS transistors with a standard (sometimes referred to here as high) threshold voltage, for example, in the region of +1 for n-MOS devices or -1 for p-MOS devices. Thus, the value of the threshold voltage in each case exceed 0.5 C. In contrast, the analog components in RF circuits, such as amplifiers, in the preferred embodiment is formed using CMOS transistors with reduced since the power the reduction of noise and greater bandwidth. The threshold voltage in the preferred embodiment, is reduced to a value close to zero, or even beyond zero. Thus, the n-MOS transistors may have a small negative threshold voltage, and the p-MOS transistors may have a small positive threshold voltage.

The dotted line 28 in Fig.1 shows one separation scheme, which is preferred at the present time. The diagram to the right from the line 28 may have transistors with high threshold voltage, while the circuit to the left of line 28 have transistors with low threshold voltages. However, there are other possible separation, and the transistors with different threshold voltages can really use in different parts of the same schema.

As disclosed in U.S. patent 5407849, it is possible to achieve different threshold voltages of the various transistors by changing the threshold doses implantation in selected parts of the semiconductor device or by using an existing mask, or by adding additional masks.

Thus, there is disclosed a structure for radio communication, which can be combined in a single chip without CCS is th stage of a radio receiver in accordance with the invention. As briefly mentioned above, this circuit includes transistors with different threshold voltages. For clarity, the drawing shows only the transistors. In Fig.2 transistors with reduced threshold voltage, is shown with thickened channel source-drain. As mentioned above, the threshold voltage of these devices can be greatly reduced in the preferred embodiment, up to values close to zero or even less zero. Devices with thresholds below zero, is called a device with depletion. The rest of the circuit is conventional, and the General design of integrated circuits to a person skilled in the art will know. The transistors may be a CMOS device or a n-MOS device or the p-MOS device.

In the General case diagram of the receiver according to Fig.2 includes an input amplifying cascade 52, the setpoint generators 54, 56 of the local oscillator and two mixer 58, 60. This scheme forms one balanced input stage. For forming a double balanced low-noise amplifier and mixer circuit can be combined with other identical schema.

Amplification cascade 52 includes two input transistors M1, M4, which are connected respectively to ground and naprajennoy transistor M4 served in inverted form. Amplification cascade 52 also includes two transistors M2 and M3 with a common gate, the gates of which are served by the voltage Vdd/2 power supply (inverted in the case of M3), and the channels of the source-drain of which is connected to the channels of the source-drain of the input transistors M1, M4.

It is clear that the cascade transistors M2, M3 with a total gate are devices with a low threshold.

The output signal of the amplifier cascade 52 is served in the in-phase mixer 58, consisting of transistors M5, M6, and in the quadrature mixer 60, consisting of transistors M7, M8.

The signal in-phase lo LOi serves on the gate of the transistor M9 and the gate of the transistor M10 served in inverted form, and the transistors M9 and M10 are connected between supply voltage Vdd and ground so that M9 and M10 form a master oscillator the local oscillator 54. The output signal from the transistors M9 and M10 are served on the gate of the transistor M8 and the transistor M5 served in inverted form.

The signal of the quadrature lo LOq served on the gate of the transistor M11 and the transistor M12 served in inverted form, and the transistors M11 and M12 are connected between supply voltage Vdd and ground so that M11 and M12 form a master oscillator heterogeneous in inverted form.

The output signal is in-phase mixer 58 is an in-phase signal IFi intermediate frequency, and the output signal of the quadrature mixer 60 is a quadrature signal IFq intermediate frequency.

It is clear that the transistors M5, M6, M7 and M8 are devices with a low threshold, and the transistors M9, M10, M11 and M12 oscillator lo belong to the type with the usual threshold. For transistor oscillator lo is preferable that the leakage currents in the off state were minimal, and therefore it is preferable to use transistors with conventional threshold. In addition, the advantage of using transistors with high or normal threshold voltage in the VCO (the generator-controlled voltage (VCO) is that it leads to a large "scale signal in the resonator and, hence, to lower (phase) noise.

The advantage of using devices with low threshold in a cascade configuration, such as the amplifier 52 will be explained with reference to Fig.3. In Fig.3 shows two cascaded transistors Q1 and Q2, which have the corresponding voltage gate-source Vgsl and Vgs2. The input signal fed to the gate of the transistor Q1 and the output signal gain at the least quite high compared with the threshold voltage Vth, so that Vgsl-Vth= 1 C. otherwise, the device will not operate in the radio frequency range. Similar considerations apply to Q2, which implies that the voltage at the gate of transistor Q2 must be installed at least about 2.8 Century, This cannot be achieved in 3-V mode, and almost certainly cannot be achieved by any mode with a lower power supply voltage. However, if the threshold voltage has been reduced, for example, to zero, then Q2 would be sufficient voltage at the gate equal to the 2nd Century

Therefore, returning to the diagram of Fig.2, one can see that the use of devices with a low threshold for cascade transistors M2, M3 with a total gate improves the dynamic range of the circuit or may be given the opportunity to use a lower supply voltage.

One of the possible problems associated with the use of devices with a low threshold, is that they have conductivity (due to the conductivity below the threshold) even when the voltage of the gate-source on them is zero. This problem is solved in the amplifier circuit 52 of Fig.2 so that the input transistors M1, M4 are the threshold of the conventional type with malyia amplifier must be disabled supply current. In this case, you must also make the connection of the transistors M1, M4 input AC current and to file them separate offset.

The advantage of using devices with low threshold in transfer valve, and the mixers 58, 60 will be explained with reference to Fig.4. In particular, in Fig. 4 shows the transmission gate consisting of two transistors, the gate of one of which Q3 is connected to the supply voltage Vdd, a gate of another of which Q4 is grounded. For each transistor voltage gate-source equal to Vdd/2. Given a threshold voltage, and ignoring the effect of reverse bias, the effective voltage of the gate is equal to Vdd/2-Vth. 3-volt mode, in which the threshold voltage is 0.8 V, this gives the effective voltage at the gate about 0.7 Century Than becomes less effective voltage of the gate, the greater the problem arising due to noise. In addition, if the supply voltage to reduce the effective voltage of the gate would be high enough to activate the shutter. If the threshold voltage is reduced to zero, then the effective voltage of the gate becomes approximately equal to Vdd/2, i.e. about 1.5 V, which is approximately equal to double the of Fig.2, you may notice that the use of devices with a low threshold for transistors M5, M6, M7 and M8 reduces noise, but also reduces the resistance of the device in the on state. Also, it becomes possible to use a lower supply voltage.

One of the likely problems associated with the use of devices with a low threshold, is that they have conductivity (due to the conductivity below the threshold) even when the voltage of the gate-source on them is zero. This issue is resolved in the schema of the mixers 58, 60 of Fig.2 so that each transistor can be properly turned off by the negative supply voltage gate-source equal to Vdd/2 and opposite to it in sign.

Thus, there is disclosed circuits of the receiver, which can effectively operate at low supply voltages without causing problems due to high leakage currents.

Claims

1. The amplifier circuit of the radio receiver, implemented on the basis of a CMOS chip comprising two channel unipolar field-effect transistor (CPU-effect transistor) with a common gate and two input CPU-effect transistor with a standard threshold voltage is of the earth", and the CPU transistors with a common gate connected in a cascade configuration between the input of the CPU-transistors, while the CPU transistors with a common gate have a reduced threshold voltage in comparison with a standard threshold voltage input of the CPU transistors.

2. Diagram of the radio-frequency mixer, implemented on the basis of a CMOS chip containing two transmission gate, each of which includes two channel unipolar field-effect transistor (CPU-effect transistor), and the corresponding signals of the local oscillator are fed to the gates of the transistors, and the input signal applied to the inputs of transmission gates, the transistors of the transfer gates have a reduced threshold voltage than transistors having a standard threshold voltage, which is used to generate signals lo.

3. Diagram of the radio frequency mixer on p. 2, in which the signals of the local oscillator serves on transmission gates two master oscillator lo, each of which is formed of two transistors, and the transistors master lo generators have a standard threshold voltage.

4. The radio is implemented on the basis of CMOS circuits, include the

 

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