• CryoHEMTs: chip or packaged in ceramic SOT23
  • CryoHEMTs based cryogenic preamplifiers

CryoHEMTs: chip or packaged in ceramic SOT23

Characteristics of available cryoHEMTs with various gate-surface measured at 4.2 K, Ids = 1 mA and Vds = 100 mV:

Denomination 200pch 100pch 30pch 5pch 1pch
LgxW (µm²) 1.5×105 6.4×104 2.0×104 2.0×103 4.0×102
Cgs (pF); Cgd (pF) 236; 8.9 103; 8.9 33; 3.5 4.6; 1.0 1.8; ~0.6
Vds(mV); Ids(mA) 100; 1.0 100; 1.0 100; 1.0 100; 1.0 100; 0.5
gm (mS); gd (mS) 52; 0.4 40; 1.2 115; 1.3 44; 1.3 15; 0.8
ft = gm/(2πCgs) (Hz) 3.5×107 6.2×107 5.5×108 1.5×109 1.3×109
en (nV/Hz½) @1Hz
@10Hz
@100Hz
@1kHz		 5.4
1.7
0.52
0.24 		6.3
2.1
0.76
0.34 		14
4.5
1.5
0.57 		30
12
4.5
1.4		 100
30
10
2.7
en-white (nV/Hz½) 0.18 0.22 0.12 0.24 0.4
in (aA/Hz½) @1Hz
@1kHz 		21
6.8×102		 15
5.1×102		 9.1
2.4×102		 2.2
70		 3.6
57
cryoHEMT chip
cryoHEMT in ceramic SOT23

LgxW is the gate surface; Cgs, the gate-source capacitance; Cgd, the gate-drain capacitance; Vds, the drain-source bias; Ids, the drain-source current; gm, the transconductance; gd, the output conductance; ft, the current-gain cutoff frequency;  en, the equivalent input noise voltage; en-white, the equivalent input white noise voltage; in, the equivalent input noise current. Noise current is measured with the help of the capacitance input setup shown in the reference Appl. Phys. Lett. 105, 13504 (2014).

CryoHEMTs based cryogenic preamplifiers

Various cryogenic readout electronics have been realized with cryoHEMTs and performed (see papers in “applications”), a few examples are as below. We can propose and provide several types of preamplifier to meet specific experimental requirement, e.g., set the output impedance of 50Ω by adding a common-drain amp for operating frequency » 1 MHz; decrease the white noise of the amps by adjusting their power consumption; minimize the Miller effect and the input capacitance by adding a follower (common-drain amp).

Wildly used preamplifier by a single 5pch cryoHEMT: specifications and some of resulted publications:

Amp box size (mm) 36×26×6
Amp model: A5-1 5pch cryoHEMT
Operating temperature ≤ 4.2 K
Voltage gain 5.5
Power consumption 0.35 mW
Input form DC coupling
Input impedance 10 PΩ* // 11 pF**
Output impedance 125 Ω
Noise voltages @ 4.2 K 1.42 nV/Hz½ at 1 kHz
0.3 nV/Hz½ at 100 kHz
0.24 nV/Hz½ at 1 MHz
Noise currents @ 4.2 K 60 aA/Hz½ at 1 kHz
0.7 fA/Hz½ at 100 kHz
2 fA/Hz½ at 1 MHz

*Input DC impedance > 10 PΩ (1016 Ω); 
**input capacitance with the Miller effect.

Proposition: low frequency amp with a 200pch cryoHEMT
Amp model: A200-1 200pch cryoHEMT
Operating temperature ≤ 4.2 K
Voltage gain 10
Power consumption 0.35 mW
Input form DC coupling
Input impedance 10 PΩ* // 250 pF**
Output impedance 200 Ω
Noise voltages @ 4.2 K 6 nV/Hz½ at 1 Hz
1.7 nV/Hz½ at 10 Hz
0.52 nV/Hz½ at 100 Hz
0.24 nV/Hz½ at 1 kHz
0.18 nV/Hz½ at 100 kHz
Noise currents @ 4.2 K 21 aA/Hz½ at 1 Hz
0.7 fA/Hz½ at 1 kHz

*Input DC impedance > 10 PΩ (1016 Ω); 
**input capacitance with the Miller effect.

Proposition: low frequency amp with two 200pch cryoHEMT
Amp model: F&A200-025 200pch cryoHEMT
Operating temperature ≤ 4.2 K
Voltage gain 10
Power consumption 0.51 mW
Input form DC coupling
Input impedance 10 PΩ* // 10 pF**
Output impedance 500 Ω
Noise voltages @ 4.2 K 8.4 nV/Hz½ at 1 Hz
2.4 nV/Hz½ at 10 Hz
0.73 nV/Hz½ at 100 Hz
0.37 nV/Hz½ at 1 kHz
0.3 nV/Hz½ at 100 kHz
Noise currents @ 4.2 K To be determined

*Input DC impedance > 10 PΩ (1016 Ω); 
**input capacitance with a drastic Cgs reduction and the suppression of the Miller effect.