Current Mirror with Buffered Multiple Stages

Current mirror with BJT. In this circuit a buffer is used to minimize the effect of the current drained by the N bases. The impact will be smaller than without the buffer. Change the switches to see the difference in the collector current and base current. Iref = (Vcc - 2*Vbe) / R - Iref: current in the resistor of 10k - 2*Vbe because of the two Base-Emitter junctions Ib_buf = Ie_buf / (Bcc + 1) - Ib_buf: base current int the buffer Iref = Ic0 + Ib_buf Iref = Ic0 + Ie_buf / (Bcc + 1) Ie_buf --> sum of base currents + 1 Ie_buf = (N + 1) * Ib Ie_buf = (N + 1) * Ic0/Bcc - where: N is the number of stages (mirrors) Finally: Iref = Ic0 + Ie_buf / (Bcc + 1) Iref = Ic0 + ((N + 1) * Ic0/Bcc) / (Bcc + 1) Iref = Ic0(1 + ((N + 1)/Bcc)/(Bcc+1)) Ps.: consider all transistor equals

published 9 years ago