| 摘要 |
An amplifier comprising an input stage (IPST) having a pair of inputs (INN,INI) for receiving a differential input signal (Vin) and a pair of outputs (CQ6,CQ7) for delivering a differential intermediate signal in response to the differential input signal (Vin); an intermediate stage (INTST) for converting the differential intermediate signal to a non-differential intermediate signal, which intermediate stage (INTST) comprises a current mirror (Q5,R5,Q4,R4) having an input branch (Q5,R5) and an output branch (Q4,R4) for receiving the differential intermediate signal; an output stage (OPST) having an input coupled to the output branch (Q4,R4) and having an output for delivering an output signal (Vout) to an output (OP) of the amplifier; and means for stabilizing the amplifier. The means for stabilizing the amplifier comprises a capacitor (CM2) coupled between the output (OP) of the amplifier and the input branch (Q5,R5). Thus, the current mirror (Q5,R5,Q4,R4) already available within the intermediate stage (INTST) is also used for signal inversion within a respective Miller loop. As a consequence, no current mirror is needed in the output stage (OPST) for the purpose of stabilizing the respective Miller loop. Thus, the inventive amplifier does not need a current mirror for driving the output stage (OPST). As a result the bandwidth of the amplifier is extended. Moreover, owing to the special manner in which the capacitor (CM2) is coupled to the input branch (Q5,R5), the inventive amplifier does not need any differential stages in the output stage (OPST), which would limit the minimum supply voltage. The above-mentioned measures provide a large bandwidth and low supply voltage amplifier.
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