Low-noise broadband amplifier dc oleksenko, kolesnikova

 

(57) Abstract:

The invention relates to electronics, instrumentation, automation, in particular for low-noise precision amplifier current in the integrated design, and can be used in the preliminary stages of devices linear current amplification. Low-noise broadband amplifier DC contains four current mirrors (TK) 1-4, connected in series between buses positive 9 negative 10 power supply, and circuit complementary output transistors (T) 5,6 and 7,8. Due to the consistent inclusion of TK 1-4 implemented active suppression of noise in the input stage TK 3 and 4 and the simultaneous formation of coherent control signals on the control electrodes of the output T of 5.6 and 7.8. Effect: reduce input capacitance and noise current amplifier. 1 C. p. F.-ly, 4 Il.

The invention relates to electronics, instrumentation, automation, in particular for low-noise precision amplifiers in integrated circuits, and can be used in the preliminary stages of devices linear current amplification.

There is a method common mode noise generated by pulsations history is Nike". - M. : Mir, 1980, S. 42-45] .

The disadvantage of the differential input stage of any of the operational amplifier is that when the occurrence of the noise signal in one of the transistors is automatically generated coherent referred noise signal, and the output of the differential input stage appears double and reinforced in time (the amount of gain transistors) control signal. After amplification control signal transistors of the output stage of the operational amplifier, the noise increases even more, resulting in significant deterioration of the signal/interference".

In this regard, the known current amplifiers operating over a wide dynamic range and low power consumption [U.S. patent 6014056, CL N 03 F 3/26, published 11.01.2000; U.S. patent 4893091, CL N 03 F 3/45, 3/30, published 09.01.1990, Fig. 4] do not have high accuracy, because they have a high input capacitance and relatively high noise parameters, reducing the precision high-frequency current amplifier.

The closest analogue is the current amplifier [ed. St. USSR 1631703, CL N 03 F 3/26, published 28.02.1991] containing the transistors of the input and output stages, four reflector takakusagi element resistor, additional transistors, bus power source and a common bus.

The inclusion of reflectors current (current mirrors) in the circuit of the current amplifier does not allow to ensure the coherence of the ripple current in each of them. In addition, the connection of some transistors with a common bus leads to the fact that their noise characteristics are also not coherent, which further degrades the signal-to-noise ratio ("SNR").

The present invention is the creation of a precision low-noise broadband amplifier, based on the coherent implementation of the method of self-compensation of noise, which reduces the input capacitance and the noise current amplifier.

The problem is solved in that implements a coherent way of self-compensation of noise current amplifier, characterized in that when the noise is automatically generated control signal, own coherent noise, which after amplification is subtracted from the amplified aggregate signal containing the signal and the noise.

The problem is solved also by the fact that low-noise broadband amplifier DC contains connected to the input electrodes kitsch second current mirror is made complementary to the first, and complementary output transistors that are series-connected between buses positive and negative power amplifier, a connection point of the output complementary transistors connected to the respective outputs of the amplifier, and between the first and second current mirrors of series-connected third and fourth current mirror which is made complementary respective to the first and second current mirrors, and a connection point of the respective output electrodes of the third and fourth current mirrors are connected to respective inputs of the amplifier, and a connection point of the respective output electrodes respectively of the first, third and second, and fourth current mirrors are connected respectively to the control electrodes of the complementary output transistors, in addition, each current mirror contains the same number of input and output electrodes. To solve this problem, the current mirror includes a reference diode connected between the reference input and reference output electrode of the current mirror, and MOS transistors, each of which is included between the respective input and output electrodes of the current mirror, the gates to masego wideband precision current amplifier. In Fig. 2. shows an example execution of the current mirrors used in this amplifier. In Fig. 3, 4 shows examples of a low noise wideband precision current amplifier, which is made on the basis of these current mirrors.

The essence of the way of coherent self-compensation of noise is that the control device sequentially enabled by the output transistors of the amplifier are automatically generated own coherent noise signals, but in opposition to those of their own noise. As a result of this formation of the control signals at the output of series-connected output transistors in opposite phase coherent signals are subtracted and the load does not, which is fully equivalent to the reduction of internal noise of the amplifier as a whole.

This method is implemented in the claimed low-noise wideband precision current amplifier shown in Fig. 1.

The amplifier includes a current mirror 1-4, the output transistors 5-8, tyres positive 9 negative 10 voltage inputs 11, 12, the outputs 13, 14. Current mirror 1 (Fig. 2) contains, for example, the reference diode 15, the transistors 16, 17, the input electrode is Yes can be used transistor in the diode-connected.

In Fig. 3 shows an example implementation of a low noise wideband precision current amplifier with one output based on current mirrors 1-4 performed on the MOS transistors 24-27, resistors 28-35 and reference diodes 36-39. In the output circuit of the MOS transistors 5, 6 includes resistors 40-43. Shows common bus 44.

In Fig. 4 shows an example implementation of a low noise wideband precision current amplifier with two outputs, made on the basis of current mirrors 1-4, which in addition to the above elements contain MOS transistors and resistors 45-48 49-56. In the output circuit of the resistors 7, 8 includes resistors 57-60.

Does the amplifier as follows.

The input signal is supplied to the inputs 11 and 12 (Fig. 1, 4) to the inputs 18 and 19 of the current mirrors 3 and 4, through the outputs 20 and 21 which are transmitted to the control electrodes of the complementary output transistors 5, 6 and 7, 8. Eventually the load that is connected to the outputs 13 and 14, between the points of connection of the output transistors), produces an amplified output signal.

Suppression of self-noise, which occurs in any of the active elements of the current mirrors 1-4, as follows. For example, has changed the capabilities on the (2), that will result in a corresponding change of currents in the cascaded current mirrors 2, 3 and 4 (1, 3 and 4). In the end, to the control electrodes of each output transistor 5-8 arrive coherent noise source signal control signals. Since the increment of the output currents of the output transistors 5, 6 and 7, 8 remain after amplification are equal, the outputs 13 and 14 of amplifier noise signal misses.

The application of the method of coherent self-compensation of noise allows you to achieve your goal of reducing the input capacitance and noise of the amplifier and thereby increase its precision.

1. Low-noise broadband amplifier current, containing connected to the input electrodes to the tires of the positive and negative power amplifier, respectively, the first and second current mirror and the second current mirror is made complementary to the first, and complementary output transistors that are series-connected between buses positive and negative power amplifier, a connection point of the output complementary transistors connected to the respective outputs of the amplifier, characterized in that between the first and second is to the first and second current mirrors, respectively, moreover, the input signal is supplied to the inputs of the amplifier to the input electrodes of the third and fourth current mirrors, and a connection point of the respective output electrodes of the first, third and second, and fourth current mirrors are connected respectively to the control electrodes of the complementary output transistors, each current mirror contains the same number of input and output electrodes.

2. Low-noise broadband amplifier current on p. 1, wherein the current mirror includes a reference diode connected between the reference input and reference output electrode of the current mirror, and MOS transistors, each of which is included between the respective input and output electrodes of the current mirror, the gates of which are connected to the reference output electrode of the current mirror.

 

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