Title :
A low-voltage programmable-gain CMOS amplifier with very-low temperature-drift
Author :
De Lima, Jader A. ; Dualibe, Carlos
Author_Institution :
Dept. of Electr. Eng., Univ. Estadual Paulista, Sao Paulo, Brazil
Abstract :
A new topology for a LVLP variable-gain CMOS amplifier is presented. Inputand load-stage are built around triode-transconductors so that voltage-gain is fully defined by a linear relationship involving only device-geometries and biases. Excellent gain-accuracy, temperature-insensitivity and wide range of programmability are thus achieved. Moreover, adaptative biasing improves the common-mode voltage stability upon gain-adjusting. As an example, a 0-40 dB programmable-gain audio-amplifier is designed. Its performance is supported by a range of simulations. For I´DD=1.8 V and 20 dB-nominal gain, one has Av=19.97 dB, f3dB=770 kHz and quiescent dissipation of 378 μW. Over temperatures from -25°C to 125°C, the 0.1 dB-bandwidth is 52 kHz. Dynamic-range is optimized to 57.2 dB and 42.6 dB for gains of 20 dB and 40 dB, respectively. THD figures correspond to -60.6 dB at Vout=1 Vpp and -79.7 dB at Vout=0.5 Vpp. A nearly constant bandwidth for different gains is also attained
Keywords :
CMOS analogue integrated circuits; SPICE; audio-frequency amplifiers; equivalent circuits; flicker noise; low-power electronics; network topology; operational amplifiers; programmable circuits; thermal noise; -25 to 125 C; 0 to 40 dB; 1.8 V; 52 kHz; LV programmable-gain CMOS amplifier; PSPICE; adaptive biasing; audio-amplifier; common-mode output voltage; common-mode voltage stability; equivalent noise circuit; flicker noise; gain-accuracy; gain-adjusting; linear relationship; nearly constant bandwidth; optimized dynamic range; quiescent dissipation; simulation; temperature-insensitivity; thermal noise; triode-transconductors; variable-gain CMOS amplifier; very-low temperature-drift; voltage-gain; wide programmability range; Audio systems; Bandwidth; Circuit topology; Complexity theory; Feedback loop; Geometry; Hearing aids; Temperature; Transconductance; Voltage;
Conference_Titel :
Circuits and Systems, 2001. ISCAS 2001. The 2001 IEEE International Symposium on
Conference_Location :
Sydney, NSW
Print_ISBN :
0-7803-6685-9
DOI :
10.1109/ISCAS.2001.921934
