Precision Buffer with Low Input Capacitance

This paper describes precision voltage follower (buffer) circuit designed for precision measurement purposes. Presented buffer was designed for use at frequencies up to 1 MHz and voltage amplitude up to 1.5 V. Buffer has input capacitance below 1 pF. Output impedance at 100 kHz is below
$11 \ \text{m}\Omega$
. Amplitude and phase transfer error is below
$2 \ \mu\text{V}/\text{V}$
and 2 μrad at 100 kHz. Error of the transfer at 1 MHz depends on the used output cable and load. The error was less than
$100 \ \mu \text{V}/\text{V}$
with the 20cm cable.