βMTX121AN

The βMTX121AN belongs to the βMTX and βMTY series of ultralow offset voltage precision preamplifiers made by IPRS Băneasa [1].

The I.P.R.S. Băneasa Full Line Condensed Catalog (1990) lists the βMTX series (βMTX121AN, βMTX121N, βMTX321AN, βMTX321N, βMTX321CN) and the βMTY series (βMTY121AN, βMTY121N, βMTY321AN, βMTY321N, βMTY321CN) as improved, easy-to-use versions of the popular LM121 precision preamplifier (see the βM121N), with a fixed input stage operating current and an internally trimmed offset voltage [1]. Unlike the standard series, they need no external components (two resistors and a low-TC potentiometer), because the current setting resistors are integrated on the chip and the offset voltage is adjusted on the chip at wafer test, down to typically ±15 µV, with the zener-zap trimming technique [1]. The βMTX series is meant mainly for low noise with low source resistance, and the βMTY series for low input bias current with high source resistance; made with a low noise bipolar process with ion-implanted super-beta transistors, their input bias current related errors are more than ten times lower than in conventional bipolar amplifiers at the same operating current, for low noise, high-accuracy amplification of very low-level signals in transducer applications [1].

The catalog gives an operating temperature of −55…+125 °C (121AN, 121N) and 0…+70 °C (321AN, 321N, 321CN), an input offset voltage of at most 75 µV (121AN, 321AN), 150 µV (121N, 321N) and 250 µV (321CN), an input offset voltage drift of at most 1 µV/°C (βMTX121AN, βMTX321AN), an input bias current of at most 10 nA (βMTY121AN) and 75 nA (βMTX121AN), common-mode and supply voltage rejection ratios of at least 120 dB, a typical input noise voltage of 7 nV/√Hz (βMTX series) and a typical supply current of 400 µA [1]. Pins (MP-48, top view): 1 output 2, 2 input 1, 3 input 2, 4 V−, 5 balance, 6 balance, 7 V+, 8 output 1 [1]. The typical application, a high precision ultra-low drift operational amplifier with a βM308A (recommended Rp: 10 kΩ for the βMTX321, 25 kΩ for the βMTY321; frequency compensation Cc (pF) = 680/ACL for the βMTX121 and 100/ACL for the βMTY121, ACL being the closed loop gain), is in the Gallery [1].