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The Improved Howland current pump is a circuit that uses a difference amplifier to impose a voltage across a shunt resistor, creating a voltage-controlled current source capable of driving a wide range of load resistances.
The “Improved” Howland current pump is a circuit that uses a difference amplifier to impose a voltage across a shunt resistor (Rs), creating a voltage-controlled bipolar (source or sink) current source capable of driving a wide range of load resistance.
There are two basic circuits --the Basic Howland Current Pump, Figure 1, and the "Improved" Howland Current Pump. The Basic circuit does good service for simple applications, but if its weaknesses are unacceptable, the "Improved" circuit may do much better for critical tasks. See Figure 5. Figure 1. The Basic Howland Current Pump
What is a buffered op amp? Buffered op amps are op amps with the ability to drive a low output resistance and/or a large output capacitance. This requires: - An output resistance typically in the range of 10 R o 1000 - Ability to sink and source sufficient current (C L·SR) Types of buffered op amps: - Open loop using output amplifiers
The virtual ground reference buffer (VGRB) technique is introduced as a means to improve the performance of switched-capacitor circuits. The technique enhances the performance by improving the feedback factor of the op-amp without affecting the signal gain. The bootstrapping
In the early days of high speed circuits, simple emitter followers were often used as high speed buffers. The term buffer was generally accepted to mean a unity-gain, open-loop amplifier. With the availability of matching PNP transistors, a simple emitter follower can be improved, as shown below in Figure 2.1A. This complementary circuit offers ...
Signal-to-Noise Ratio (SNR): the ration of the signal power to the noise power at the output. The sources of noise are the input and output buffer, switch, and clock jitter. Signal to Noise + Distortion Ratio (SNDR): the ration of signal power to the total noise and harmonic power at the output.
