EP0655841A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
DC voltage offset compensation
Assignee: Nokia Oyj
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Filing: 1994-11-23
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Granted: —
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Expires: 2014-11-23
Abstract
Abstract The object of the invention comprises a method and a device for compensating the DC offset (dU) of a D/A converter (2) particularly in the base frequency modulator of a mobile phone. The method and the device use an error correction register (5), whose value is changed on the basis of the DC offset, and which is added to each signal sample to be converted for compensating the DC offset. The value of the error correction register (5) is changed in the testing mode so that a preset control value is fed into the D/A converter (2), corresponding to the zero voltage of the output of an ideal D/A converter; the voltage values of the outputs of the differential output pair (2a, 2b) arranged in connection with the D/A converter (2) are compared to verify the polarity of the voltage difference (dU) of the outputs and the polarity, i.e. the sign, of the relative DC offset; and, on the basis of the polarity of the voltage difference (dU), the value of the error correction register (5) is either decreased or increased by one from the preset initial value which is preferably zero.
Inventors
- 👤 Pekka Mikkola
- 👤 Markku Lintinen
- 👤 Jukka Ranta
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 10:39
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/10; H03M1/1009; H03M1/1014; H03M1/1019; H03C; H03C3/00; H03C3/38; H03C3/40; H03M1/06; H03M1/0617; H03M1/0675; H03M1/0678; H03M1/068; H03M1/0682; H03M1/66
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
91 words
A method for compensating for an offset in a signal of an electronic device (2; 8), comprising the steps of: inputting a predetermined signal to the electronic device (2; 8); deriving an error signal indicative of a difference between an ideal output and an actual output from the electronic device (2; 8) each corresponding to the predetermined signal; modifying a compensation value stored in a memory means (5; 12, 13) in accordance with the error signal; and adding said value to a subsequent signal input to the electronic device (2; 8).
Claim 2
Dependent Claim
27 words
A method according to claim 1, further comprising repeating said steps with the subsequent signal being the predetermined signal until said difference passes through a minimum value.
Claim 3
Dependent Claim
16 words
A method according to claim 1 wherein the electronic device (2; 8) is a D/A converter.
Claim 4
Independent Claim
19 words
A method according to any preceding claim, wherein the error signal is indicative of the polarity of the difference.
Claim 5
Independent Claim
26 words
A method according to any preceding claim, wherein the electronic device (2; 8) has differential pair output port and the actual signal is a differential signal.
Claim 6
Independent Claim
15 words
A method according to any preceding claim, wherein the predetermined signal has substantially zero magnitude.
Claim 7
Dependent Claim
29 words
A method according to claim 5 or claim 6 dependent on claim 5, wherein the error signal is indicative of the difference between respective signals of the differential signal.
Claim 8
Independent Claim
36 words
A method according to any of claims 4 to 7, wherein the value stored in the memory means (5; 12, 13) is incremented if the said polarity is negative and decremented if the polarity is positive.
Claim 9
Dependent Claim
35 words
A method according to any of claims 4 to 8 dependent on claim 2, wherein the passing of the difference through a minimum value is indicated by a change in the polarity of the difference.
Claim 10
Independent Claim
20 words
A method according to any preceding claim, wherein said steps are performed during periods of non-use of the electronic device.
Claim 11
Dependent Claim
99 words
Apparatus for compensating for an offset in a signal of an electronic device (2; 8) comprising input means (1; 7) for inputting a predetermined signal to the electronic device (2; 8); detecting means (4; 10, 11) for detecting a difference between an ideal output and an actual output from the electronic device (2; 8) each corresponding to the predetermined signal; modifying means for modifying a compensation value stored in a memory means (5; 12, 13) in accordance with the detected difference; and adding means for adding said value to a subsequent signal input to the electronic device (2; 8).
Claim 12
Dependent Claim
15 words
Apparatus according to claim 11, wherein the electronic device (2; 8) is a D/A converter.
Claim 13
Dependent Claim
24 words
Apparatus according to claim 11 or claim 12, wherein the detecting means (4; 10, 11) is adapted to detect the polarity of the difference.
Claim 14
Dependent Claim
30 words
Apparatus according to any of claims 11 to 13, wherein the electronic device (2; 8) has a differential pair output port for outputting the actual signal as a differential signal.
Claim 15
Dependent Claim
32 words
Apparatus according to any of claims 11 to 14, wherein the input means (1; 7) is adapted to input a predetermined signal of substantially zero magnitude to the electronic device (2; 8).
Claim 16
Dependent Claim
29 words
Apparatus according to claim 14 or claim 15 dependent on claim 14, wherein the detecting means is adapted to detect the difference between respective signals of the differential signal.
Claim 17
Dependent Claim
36 words
Apparatus according to any of claims 13 to 16, wherein the value stored din the memory means (5; 12, 13) is incremented if the said polarity is negative and decremented if the said polarity is positive.
Claim 18
Dependent Claim
37 words
Apparatus according to claim 13 or any of claims 14 to 17, dependent on claim 13, wherein the passing of the difference through a minimum value is indicated by a change in the polarity of the difference.
Claim 19
Dependent Claim
31 words
Apparatus according to any of claims 11 to 18, wherein the input means (1; 7) inputs a predetermined signal to the electronic device (2; 8) when it is not in use.
Claim 20
Dependent Claim
36 words
Apparatus according to Claim 19, comprising equipment (15) for detecting free time slots or non use of the electronic device (2; 8) when the value stored in the memory means (5; 12, 13) can be updated.
References Cited (Backward Citations)
EP0605883A2
Cited
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