Pluto Instruments

PCG-minis are compact size and fixed gain current preamplifiers designed to use with a cryogenic scanning tunneling microscope and spectroscopy for quantum materials research. Minis are specially designed for the lowest noise and reasonable bandwidth without destroying the advantage of the low thermal current noise floor of the high ohm feedback resistors for very tiny tunneling current.

PCG-mini-9G

1. PCG-mini-9G has a signal bandwidth of ~4 kHz and it is stable in the presence of 1 nF input capacitance.

2. Noise floor is 4 fA/√Hz.

3. High sensitivity RMS voltmeter reads full band integrated output voltage noise (input current noise) as

a. ~ 400 µVrms (400 fArms) for shielded open input

b. ~ 740 µVrms (740 fArms) for 200 pF input capacitance

c. ~3.6 mVrms (3.6 pArms) for 1 nF input capacitance

4. Input bias current is less than 100 fA.

5. Input offset voltage can be trimmed for precision measurement and higher power supply rejection ratio.

PCG-mini-10G

1. PCG-mini-10G has 10 times higher sensitivity relative to 9G unit. A true single 10 GΩ feedback resistor used.

2. Noise floor is 1.3 fA/√Hz.

3. Signal bandwidth is ~ 3 kHz. (stray capacitance ~5 fF)

4. Stable in the presence of 1 nF input capacitance

(perfectly stable up to 0.5 nF)

5. High sensitivity RMS voltmeter reads full band integrated output voltage noise

(input current noise) as

a. ~ 1.2 mVrms (120 fArms) for shielded open input

b. ~ 4 mVrms (400 fArms) for 200 pF input capacitance

c. ~ 10 mVrms (1 pArms) for 500 pF input capacitance

6. Input offset voltage can be trimmed for precision measurement and a higher power supply rejection ratio.

The above noise spectral density plots (open and in the presence of 1 nF input capacitance) show that PCG-minis' noise floors are virtually the same as the theoretical limits of the feedback resistors' noises