Low level transistorized chopper amplifier

Low-level transistorized chopper amplifiers have been constructed for a specific missile application. With minor modifications, these amplifiers can meet the requirements for general usage. The chopper is capable of processing 900 signals per second at a common mode rejection of 1000:1. The gain is smoothly adjustable ± 20 percent of full scale and the output is linear within 1 percent of a straight line drawn between the end points. Operation is consistent over a temperature range of +40°F to 165°F with less than 10 percent variation in gain. The amplifier's rise time is less than 300 microseconds. Input impedance is 25 k or better and output impedance is 5 k or less. Ripple is less than 10 millivolts peak.