FI109159B - A method for controlling analog components of an integrated circuit - Google Patents

Abstract

Analog circuit parts in an integrated circuit, for example filters, can be equalized by a control current by equalizing an additional reference circuit part, whose equalization must be verified externally, with this control current. By using a suitably designed horizontal frequency oscillator whose equalization must also be verified, this reference circuit part can be dispensed with even in known TV receivers. Using additional control circuits in the integrated circuit, fine equalization of the various circuit parts can be carried out automatically by adding a small correction control current to each control current. As a result, the control circuits are free from problems related to background noise, interception range and component tolerances. Equalization of analog bipolar or CMOS integrated circuits.

Description

5,109,159

Method for Adjusting Analog Parts of Integrated Circuit - Förfarande för justering av analogoga delar i en integrerad krets

The invention relates to a method for adjusting analog parts of an integrated circuit.

For the manufacture of 'One-chip' TV receivers, the analog components in the integrated circuits, such as the filters, need to be adjusted due to component tolerances and manufacturing mismatch. From Y.P. Tsividis, known as "MOW Analog IC Design - New Ideas, Trends and Obstacles", ESSCIRC'86, Delft Conference Proceedings, is known for adjusting an integrated circuit reference element, which is structurally similar to other adjustable elements of an integrated circuit, and obtaining at least an approximate adjustment of the other adjustable elements. Adjusting this reference element will, however, involve an additional cost. Furthermore, this does not take into account the component tolerances of the integrated circuit.

The object of the invention is to adjust the analog parts of the integrated circuit at a low cost and with high accuracy.

25; This problem is solved by the claims set forth in claim 1; A hallmark. Preferred variations of the invention are set forth in the dependent claims.

• · · 30 A reference circuit of the integrated circuit, which also exists: exists in known television receivers and is adjustable, in the same way as other adjustable analog parts of the circuit. This reference part is, for example, a horizontal frequency oscillator and other circuit anatems, · 35 logical parts are, for example, analog filters, FM demodulators and an equalizer.

2,109,159

These parts of the circuit can be adjusted e.g. The adjusted current for the horizontal frequency oscillator is then a measure of the corresponding control current of the analog parts of the circuit.

5 For fine tuning of the analog parts of the circuit, the adjustment requires only a small change in current and only a very limited operating range. Advantageously, this control mode, e.g. noise and component tolerances, has only a minor effect. There is no problem with the 'hit' of the control circuit. Advantageously, by integrating these parts of the circuit, expensive ceramic filters and LC circuits can be omitted compared to known television receivers.

An embodiment of the invention will now be described with reference to the drawings. In them: Figure 1 is a block diagram of a multinormal television frame according to the invention; Figure 2 shows a block diagram of a signal processor included in a multi-standard television frame; Figure 3 shows a basic biguad filter cell; Figure 4 shows a gm amplifier type 1; Fig. 5 shows a gm amplifier type 2; Figure 6 shows a control wood according to the invention.

Fig. 1 shows a block diagram of a television receiver. In principle, these units correspond to units of existing television receivers. PIF stands for Picture Intermediate Frequency Branch, SIF ·, ·, · stands for Audio Intermediate Frequency Branch. However, in the television frame of the invention, the units within the dotted dash mark and the adjustable analog portions of the circuit therein are contained within a single integrated circuit ('one chip').

Fig. 2 is a detailed block diagram of the integrated circuit 5 with different adjustable parts of the circuit. These circuit sections are designated 20 (horizontal frequency oscillator), 211-214 (vt filter), 221-224, 231-234 (audio filter), 24 (chrominance clock filter), and 25 (chrominance trap).

10

Figure 3 illustrates a basic biquad filter cell used several times in an integrated circuit and a transfer function Vout associated therewith. The following table shows the different filter characteristics of these basic filter cells depending on the connections of the inputs Va, Vb and Vc.

Low Pass: Vb and Vc in ground, Va input signal

Overpass: Va and Vb in ground, Vc input signal

Bandwidth: Va and Vc in country, Vb Input signal 20 Trap: Vb in country, Va and

In Vc the input signal

The basic biquad filter cell of Figure 3 includes two gm amplifiers (transconductance amplifiers) having a coupling according to Fig. 25 4 and Fig. 5. Type 1 GM amplifiers': Can handle higher frequencies than type 2 GM amplifiers. In order to increase the signal amplitudes to be processed, jm type 1 amplifiers have two diodes connected in series with the emitters of Fig. 4. The second connection 30 allows further processing of the type 2 GM amplifier of Figure 5. : higher signal amplitudes and lower temperature, ·; · [dependence, but still require slightly higher component costs. The integrated i »·. ·. · * Circuit of Figure 2 uses both types of gm amplifiers.

35

Corresponding to the value of the capacitance CO, the average frequency of the basic biquad filter cell of FIG. 3 can now be simply adjusted by means of the current Ie or the currents Ie and II according to the equations shown in figures 3-5.

Vt is a known temperature voltage and its value is 26 mV / K.

The control tree of Figure 6 shows a horizontal frequency oscillator 60.

It is the reference portion of the circuit. Its frequency can easily be measured and adjusted with a 5-bit D / A converter 601 with less than +1% error. The D / A converter 601 can be programmed in television production, whereupon the adjustment is stored in the memory.

Due to the high voltage peaks around this D / A converter, the contents of the memory may change in an undesirable manner. If the horizontal frequency were then too low, the horizontal offset output and the chopper ac adapter could be destroyed. Therefore, the D / A converter 601 is subjected to a parity check. If this check produces an error, switch 602 controls the maximum control current. This will increase the horizontal frequency and avoid destruction of the circuits.

20

When the horizontal frequency oscillator 60 is adjusted, the control current Ie is obtained from the reference current Iref = Vref / Rext. Due to manufacturing tolerances, for example, capacitors in the integrated circuit have a true value Cactual compared to a set value Cnominal. Thus, the control current Ie is adjusted to a-; · Passively ('capacitor adjusted') and has e.g.

value Ie = Iref * Cactual / Cnominal. Cactual is practically indirectly measured by frequency measurement of a horizontal frequency oscillator 60.

30; Although the output frequency of the horizontal frequency oscillator is »» »substantially dependent on the control current Ie, it also depends, e.g., * * only slightly on the temperature voltage and the peak-to-peak output voltage Vpp. Thus, this frequency is about Ic / Cactual *:: 35 (1 + 9 * Vt / Vpp) and thus, the analog parts of the circuit controlled by the control current Ie have yet to be determined! fine adjustment.

5,109,159 As a result, the integrated circuit has five control loops for different parts of the circuit which combine the control current Ie with the correction current (Icon) at the summing points 616, 626, 636, 646 and 676.

5

Analog filters 621 to 623 and FM demodulator 624 provide a first audio channel, analog filters 631 to 633 and FM demodulator 634 provide a second audio channel. The criterion for fine tuning of each audio channel is 10 DC voltage deviations at the outputs of the FM demodulators 624 and 634, respectively. The output voltages are filtered by low-pass filters 625 and 635, respectively, with a cut-off frequency of 10 Hz. The DC sections thus obtained form the correction current Icon in each case.

The fine tuning of the sound traps 611 to 612 and the equalizer 613 in the intermediate frame portion and of the preselection filter 614 in the audio selected portion is performed by means of an additional reference biquad filter 617 arranged in 20 PLL loops. The phase-locked PLL loop includes a reference oscillator 615 and a programmable I divider 618. Then, the cut-off frequency of the reference biquad filter 617 is set to the frequency of the sound traps 611 to 612, the equalizer 613 and the pre-filter 614 so that good fit.

Because sound traps 611 - 612, equalizer 613 and preselection! for the equalizer 614, because of the high frequency to be processed, type 1 gm amplifiers are applied, the control current Ie in circuit 619 is still temperature dependent: correction.

* · »

The fine-tuning of the chrominance clock filter 64 can only result in an error of up to + 0.4%. In addition, the chrominance— '»35 of the clock filter has a value of 64 which should increase to sixteen. For this purpose, a different fine-tuning method is used. During vertical line restoration (frame), this »6 109159 filter is switched to control mode. The crystal oscillator 641 at a PAL color carrier frequency of 4.43 MHz is coupled to the filter, and the phase comparator 642 compares the filter inputs to the output phases. If the phase difference is zero, the center frequency of chrominance-5 clock filter 64 is equal to the frequency of the PAL color carrier. Phase comparator 642 is associated with sampling and holding circuit 643. Because small leakage currents are required, sampling and holding circuit 643 has an operational amplifier with NMOS inputs (not shown). It is accompanied by an integration market 644 which provides a correction current for the control current le. In addition, during the measurement, a small correction factor of about 2.3% is applied to the correction circuit 645 because the chrominance clock filter 64 has a set center frequency (4.328 MHz) slightly different from the PAL carrier frequency (4.43 MHz).

15 Adjusting the Color Carrier Trap 65 is not that critical. The same control current as that used for the chrominance-clock filter 64 is used.

The control current correction value for the vertical sync separator 671, 20 for the Fii2 loop circuit 672 and the switching power supply pulse width modulator 673 is obtained from the second PLL loop by reference integrator 674.

i:

The described adjustment method with automatic fine-tuning is applicable to integrated circuits implemented by bipolar and BICMOS technology. The additional fine-tuning, i.e., the temperature dependence of the circuit parts is preferably also minimized.

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Claims (10)

A method of controlling the analog parts of an integrated circuit (Figure 2, Figure 6) by the control current (Ie) to the components of the circuit and by a common coarse setting of several parts of the circuit, a value (Iref) equal to corresponds to the size of the control current stored in the integrated circuit or a device containing this integrated circuit, characterized in that the required control current is obtained by a regulation of a reference part (60) 20. the integrated circuit, and that during the use of the integrated circuit, an additional fine adjustment of a second part or other parts (621-624, 631-634, 614-613, 671-674, 64, 65) of the integrated circuit by means of control circuits included in the integrated circuit, which control circuits respectively add to the control current. (Ie) a correction control current (Icon). Method according to claim 1, characterized in that the reference part (60) of the circuit is controlled by the control current: T: (Ie). 30 Method according to Claim 1 or 2, characterized in that a horizontal frequency frequency (60) is used as a reference part of the circuit. Method according to any of claims 1-3 above, characterized in that the control of the reference part (60) of the circuit in connection with the manufacture of the device, which device comprises the integrated circuit, takes place. Method according to any of claims 1-4 above, characterized in that a D / A converter (601) is used for setting the control current (Ie), the control current obtaining a fixed value if an undesirable change of the control current stored in the memory is indicated by a continuous parity check. Method according to any of claims 1-5 above, characterized in that the control is by means of a control current (Ie) or respectively. by means of a correction control current (Icon) has been adapted for components according to BICMOS or bipolar technology. Method according to any of claims 1-6 above, characterized in that the low-pass filtered part of the output of the controlled FM demodulator (624, 634) and / or the output of a PLL loop which - shows a control current adjustable reference filter (615) and / or the output of a control loop having a reference current adjustable reference integrator (674), and / or the output of a control loop having one with a phase comparator (642), an integrator (644) or with '*. · A control current adjustable clock curve filter (64) is used as measured for the correction control current (Icon), wherein the input to the clock curve filter (64) is periodically connected for a first time period to a measurement signal (641) and during one: second period a known signal to be filtered, and the correction control current (Icon) is thus obtained during the first time period and it pours its value during the second a time period. »« Method according to claim 7, characterized in that the control current is further converted during the first and second time periods by two different factors (645), wherein. especially the first time period is the image rendering device in the vertical return time of the image. Method according to any of claims 1-8 above, characterized in that the control current (Ie) is additionally temperature-compensated (619) for one or more circuit parts. An integrated circuit for a device which processes a television signal, which circuit includes a horizontal frequency oscillator (60), an image intermediate frequency filter (611-613), an audio intermediate frequency filter (614), a reference oscillator (615), a filter (621-623 ) and an FM demodulator (624) for a first audio channel, filter (631-633) and an FM demodulator (634) for a second audio channel, a clock curve filter (64), a chrominance trap (65), a reference integrator (674), a vertical synchronization separator (671), a Fi2 loop loop (672) and a pulse width modulator (673) for a hacker power source, characterized in that the integrated circuit is controlled by a method according to any of claims 1- 9 above. * »I