公开(公告)号：JP2001077693A

公开(公告)日：2001-03-23

申请号：JP2000235178

申请日：2000-08-03

Applicant: LUCENT TECHNOLOGIES INC

Inventor： LOPATA DOUGLAS D ,  MALCOLM HAROLD SMITH

IPC: H03M1/76 ,  H03M1/66

Abstract: PROBLEM TO BE SOLVED: To simplify constitution by providing an array of resistors, which are composed of resistances coupled to a reference power source in series and generate analog voltages at respective taps and coupling multiple sets of multiple switches coupling desirable taps and an output node with a coded signal to one resistor array in common. SOLUTION: A resistor array 14 is composed of resistances R1 to Rn coupled with the reference power source 12 in series and generate necessary analog voltages at respective taps T1 to Tn+1. Switches M11 to Mn+11 forming a 1st switch S1 receives the control signal from a switching transistor selecting and drive circuit 18 and sends the analog voltages of the corresponding taps T1 to Tn+1 to a 1st output node 16. Then 2nd, 3rd, etc., sets of switches S1, S2, etc., receive control signals from respective switching transistor selecting and drive circuits 28, 38, etc., and send the corresponding analog voltages to 2nd, 3rd, etc., output nodes 26, 36....

公开(公告)号：JP2003234641A

公开(公告)日：2003-08-22

申请号：JP2003007039

申请日：2003-01-15

Applicant: LUCENT TECHNOLOGIES INC

Inventor： FRATTI ROGER A ,  LOPATA DOUGLAS D

IPC: H03H19/00

Abstract: PROBLEM TO BE SOLVED: To implement circuits with switched capacitors, such as a ladder filter, so that they can be continuously tuned. SOLUTION: In an integrated circuit with the switched capacitor, the switched capacitor is implemented as a DC-isolated variable capacitor. The DC-isolated variable capacitor is implemented as a T-structure having three capacitors in which one of the three capacitors is implemented with a buffer amplifier configured to receive a control signal and to apply a buffered control signal to an active device having a capacitance that is dependent on the level of the buffered control signal. In one embodiment, the capacitor C 2 of the T-structure is implemented using a voltage-controlled buffer 402 and a varactor diode 404. The buffer 402 is a high-impedance output buffer that provides isolation and preconditions and/or scales a control voltage. COPYRIGHT: (C)2003,JPO

公开(公告)号：JP2000059179A

公开(公告)日：2000-02-25

申请号：JP20518299

申请日：1999-07-19

Applicant: LUCENT TECHNOLOGIES INC

Inventor： FRATTI ROGER A ,  LOPATA DOUGLAS D

IPC: H03H19/00

Abstract: PROBLEM TO BE SOLVED: To continuously adjust a circuit provided with a switched capacitor like a ladder type filter. SOLUTION: For this integrated circuit provided with the switched capacitor, the switched capacitor is realized as a DC insulation variable capacitor. The DC insulation variable capacitor is realized as a T structure provided with three capacitors and one of the three capacitors is realized together with a buffer amplifier. The buffer amplifier receives control signals and inputs buffered control signals to an active device provided with capacitance depending on the level of the buffered control signals. For instance, the capacitor C2 of the T structure is realized by using a voltage control buffer 402 and a varactor diode 404. The buffer 402 is a high impedance output buffer for providing insulation and adjusting or increasing/decreasing a control voltage beforehand.