| 摘要 |
PCT No. PCT/GB82/00070 Sec. 371 Date May 5, 1983 Sec. 102(e) Date May 5, 1983 PCT Filed Mar. 4, 1982 PCT Pub. No. WO83/03177 PCT Pub. Date Sep. 15, 1983.A gain regulation circuit e.g. for a telephone subscriber's instrument, includes a plurality (2n+1) of long tailed transistor pairs one of which has a significantly higher gain than the remainder (2n). The circuit may be adjusted to a composite gain value between limits defined by the high and low gain pairs by providing a suitably weighted combination of these pairs. Typically, this weighting is achieved by control currents fed into the tail circuits of the pairs.
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