Circuit Forms Adjustable Bipolar Clamp

The easy-to-clamp a signal to a given value are to use the Zener diodes, connected back-to-back. This method has several disadvantages. The accuracy of the clamping depends on the tolerance of the Zener diodes, and the clamping are not adjustable, except by C Hanging diodes. The circuit in Figure 1 are a bipolar clamper with a range of±1 to±10v, with the clamping level a function of the input V_{CLAMP. Ic1 A, IC1 B, and IC3Aare Unity-gain buffers. Ic2 A is a positive clamper, and IC2 B is a negative clamper. Figure 2 shows the transfer function, with VCLAMP set at–5v. Can change VClampover the range of–1 to–10v and thereby change the clamping level. If VIn is Within–vCLAMP to +vCLAMP, then VOut=vIn. If VIn exceeds VCLAMP, then VOut=vCLAMP. To explain how the circuit works, assume four cases, with four values of VIn . Basically, the circuit works in both modes:the linear mode, in which diodes D1 and D2 is open switches, a nd the clamped mode, in which the diodes is closed switches. Table 1gives Results for the four cases. In case A, the input is 7V, VCLAMP is–5v, D1 conducts, and D2 are an open switch. The feedback loop around IC2A regulates the anode of D 1 to 5V and the output of theIC2A to 4.4V. In cases B and C, both diodes is open switches. In case D, D2 conducts, and D1 are an open switch.}

Circuit Forms Adjustable Bipolar Clamp