high gain and balanced output balun–lna employing positive feedback technique for tuner of digital televisions

High gain balun-low-noise-amplifier (lna) is proposed for tuner of digital televisions (dtvs). the proposed balun-lna is based on cs-cg (common-source-common-gate) structure. to improve the isolasion and frequency response, balun-lna has cascode transistors before load resistors. balun-lna uses current-bleeding circuit to increasie transconductance of cs transistor, so that current-bleeding transistor has transconductance of n-1 times larger than transconductance of cascode transistor. thereby, transconductance and current of cs transistor are increased n times, as n-1 times of current pass to current-bleeding transistor. therefore current of cg and cs stages stay identical. also, balun-lna employs a positive feedback to satisfy input impedance matching and cg transistor has higher transconductance. by increasing transconductance of cs and cg transistors, the proposed balun-lna achieves to high voltage gain. accordingly, cg and cs tansistors have symmetrical currents and loads at the differential output of the proposed balun-lna. symmetrical loads cause the balanced differential outputs. this proposed balun-lna is designed in 90-nm cmos technology and covers the frequency range of 40 mhz to 1ghz. this balun-lna achieves the voltage gain of 22.6 db, s11 of less than -10 db and the minimum nf of 5 db. this balun-lna operates at the nominal supply voltage of 2.2v.

high gain and balanced output balun–lna employing positive feedback technique for tuner of digital televisions

high gain balun-low-noise-amplifier (lna) is proposed for tuner of digital televisions (dtvs). the proposed balun-lna is based on cs-cg (common-source-common-gate) structure. to improve the isolasion and frequency response, balun-lna has cascode transistors before load resistors. balun-lna uses current-bleeding circuit to increasie transconductance of cs transistor, so that current-bleeding transistor has transconductance of n-1 times larger than transconductance of cascode transistor. thereby, transconductance and current of cs transistor are increased n times, as n-1 times of current pass to current-bleeding transistor. therefore current of cg and cs stages stay identical. also, balun-lna employs a positive feedback to satisfy input impedance matching and cg transistor has higher transconductance. by increasing transconductance of cs and cg transistors, the proposed balun-lna achieves to high voltage gain. accordingly, cg and cs tansistors have symmetrical currents and loads at the differential output of the proposed balun-lna. symmetrical loads cause the balanced differential outputs. this proposed balun-lna is designed in 90-nm cmos technology and covers the frequency range of 40 mhz to 1ghz. this balun-lna achieves the voltage gain of 22.6 db, s11 of less than -10 db and the minimum nf of 5 db. this balun-lna operates at the nominal supply voltage of 2.2v.