Device for amplifying digital signals

• US 6,140,875 A
• Filed: 08/05/1998
• Issued: 10/31/2000
• Est. Priority Date: 08/12/1997
• Status: Expired due to Term

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Philips, Kathleen J. P., Van Den Homberg, Johannes A. T. M.
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): NGUYEN, KHANH V
• Application Number:
  US09/129,498
• Time in Patent Office: 818 Days
• Field of Search: 330/251, 330/10, 330/207 A, 330/9
• US Class Current: 330/251
• CPC Class Codes: H03F 2200/331 Sigma delta modulation being used in an amplifying circuit
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers

Abstract

The device for amplifying digital signals includes an input electrode (10) for receiving a digital signal. The device further includes a subtraction unit (12) for subtracting at least two signals from each other, and the input electrode (10) is coupled to a first input (11) of the subtraction unit (12). The device also includes a time-continuous loop filter (14) coupled to an output of the subtraction unit (12), and a time-continuous comparator (16) and a switching amplifier (18) which are coupled in cascade to the time-continuous loop filter. The device additionally includes an output electrode (20) which is coupled to an output (22) of the switching amplifier (18). This output (22) of the switching amplifier (18) is also coupled to a second input (13) of the subtraction unit (12).

Claims

1. A method for amplifying digital signals, said method comprising the steps:

receiving a digitally encoded signal;

feeding back an amplified version of the digitally encoded signal;

amplifying said fed back amplified version of the digitally encoded signal;

subtracting said amplified fed back amplified version of the digitally encoded signal from the received digitally encoded signal forming a resultant signal;

time-continuously filtering the resultant signal;

time-continuously comparing the filtered resultant signal with a reference signal forming a control signal; and

controlling a switching amplifier with said control signal to form said amplified version of said digitally encoded signal.

2. The method as claimed in claim 1, wherein in said subtracting step, said amplified version of said digitally encoded signal is fed back from said switching amplifier substantially independent of frequency.

3. The method as claimed in claim 1, characterized in that in said time-continuous comparing step, said reference signal is said digitally encoded signal.