Patent ID: 6052001
Filing Date: 2000-04-18
Classification: H03F,H03G,H03H

Abstract:
The variable transconductance circuit comprising:at least first and second transconductance cells, each cell having a commonly connected output terminal and a respective transconductance value, wherein each respective cell operably generates a current which is proportional to an input signal voltage according to the respective transconductance value; andat least one selector circuit connected to a corresponding transconductance cell, wherein said selector circuit operates at least one of said first and second transconductance cells according to a select signal received by said selector circuit for variably establishing an effective transconductance of said variable transconductance circuit appearing at said commonly connected output terminal;wherein each of said transconductance cells comprises:a current source for supplying a constant current; anda first MOS transistor connected between said current source and a ground terminal, for receiving said input signal voltage through a gate electrode; andwherein said selector circuit comprises:a first switch for switching on or off a supply path of an externally supplied current bias to the current source of said corresponding transconductance cell according to said select signal; anda second switch for switching on or off a supply path of said input signal voltage to the gate electrode of said first MOS transistor of said corresponding transconductance cell according to said select signal, said second switch being interlocked with said first switch.