JPH02218206A - Ic for power amplification - Google Patents

Abstract

PURPOSE:To reduce the variance of a gain and to make design and production, etc., easy by forming respective resistors and amplifiers, for which the gain is determined by BTL(Balanced Transformer Less) connection in the same chip, setting one part of the respective resistors in an unusable state in the case of dual connection and using the respective resistors in the case of the BTL connection. CONSTITUTION:A first figure is the example of the dual connection and a resistor RE to be connected to a terminal 112 is short-circuited by wiring passing through a terminal 113. Then, a terminal 114 is floating. Accordingly, a signal from an input signal source 1 is amplified respectively by amplifiers 3 and 4 in an IC part 2 for amplification and sent to a load 5. A second figure is the example of the BTL connection and in this connection, when a switch 12 is turned to a fixed contact (b) side, the resistor RE to be connected to the terminal 112 is in a usable state. Terminals 114 and 115 are short-circuited by the wiring and this route is in the usable state. Accordingly, signals from input signal sources 1 and 3 are amplified by the amplifiers 3 and 4 in the IC part 2 for amplification and sent to the load 5.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to a power amplification IC (integrated circuit),
It is especially used for audio.

(Conventional technology) Conventionally, power amplification ICs have dual (Dua)
l) Connection method and BTL (BalancedTr)
It is possible to use any of the following connection methods. However, the resistor for the feedback circuit is externally attached at least in the BTL connection.

Figure 3 shows a specific example of dual connection, and Figure 4 shows a specific example of BTL connection, where 1 is an input signal source, 2 is a power amplification IC section, 3, 4
is an amplifier (op-amp), and 5 is a load. Also RF
r R9, RE r RA r RB are resistors that determine the gain, but in the BTL connection example in Figure 2, RE, RA, R
B is externally attached.

(Problems to be Solved by the Invention) As mentioned above, conventional power amplification ICs require external resistors, especially in BTL connections, so closed-loop voltage gain (
(hereinafter referred to as gain) is the resistance RF in the power amplifying section 2.
, R8 and the external connection are determined by the ratio of the resistor R5°RA + RB, so there is a drawback that the gain varies due to variations in either one. Also dual connection and BTL
Since the connections have different circuit configurations, these must be used depending on the use, which requires time and effort in designing, manufacturing, and using.

Therefore, it is an object of the present invention to reduce gain variation and improve I
An object of the present invention is to provide a power amplification IC that is easy to design and manufacture.

[Structure of the invention]

(Means and effects for solving the problem) The present invention forms each resistor that determines the gain and the amplifier in the same chip by BTL connection, and in the case of dual connection, leaves a part of each of the resistors in an unused state. The power amplification is characterized in that the above-mentioned respective resistors are used when the dual connection and the BTL connection are made, and the use switching between the dual connection and the BTL connection is performed by switching a switch and selectively using the presence or absence of wiring. This is an IC for use.

That is, in the present invention, since it is easy to keep the ratio between the respective resistance values of the IC constant during IC manufacturing, each resistor that determines the gain of the amplifier is formed in the same chip. In addition, since dual connection and BTL connection have some similar configurations, each resistor that determines the gain is unified on the BTL connection method side, and the selection between dual connection and BTL connection can be made by changing the switch and changing the wiring. This is done based on presence or absence.

(Example) The present invention will be described in detail below with reference to the drawings. Figure 1,
Figure 2 is a circuit diagram of the same embodiment;
Since this is an example corresponding to that in FIG. 4, the corresponding parts will be given the same reference numerals and the explanation will be omitted, and the characteristic points will be explained. 111 to 119 in Figures 1 and 2
is an external lead-out terminal of IC chip 2, 12 is a switch, a,
b is its fixed contact.

FIG. 1 shows an example of dual connection, in which the resistor RE connected to the terminal 112 is short-circuited by the wiring passing through the terminal 113.
Further, the terminal 114 is floating. Therefore, the signal from the input signal source 1 is transmitted to the amplifier 3 of the amplification IC section 2.
, 4 and sent to the load 5. The gain GV at this time is determined by .

FIG. 2 shows the BTL connection, and if the switch 12 is on the fixed contact side, the resistor RE connected to the terminal 112 is in use. Further, the terminals 114 and 115 are short-circuited by wiring, and this yarn path is in a used state. Therefore, the signals from the input signal sources 1 to 3 are transmitted to the amplifier 3 of the amplification IC section 2.
and 4, and sent to load 5. Gain G at this time
v2 is determined by .

As shown in FIGS. 1 and 2, the resistance RA of the feedback circuit.

By incorporating all of RB + RE and R9 + RF in the open-IC section 2, the gain G1 is determined by the resistance ratio of rRp + R8J and R5 from equation (1), and the gain GV
2 is rR3+RE 10Rp J and rRs from equation (2)
+REJ resistance ratio, and r (RA+Rs)(RE
+ RS+ RA/R8) J and “RB-RF”
It is determined by the resistance ratio of By the way, since the values of each resistor produced under the same conditions as in an IC vary in the same way, the variations in the respective resistance ratios are relatively canceled out, and therefore the gain Gvl.

GV2 is made constant.

In other words, as in the conventional example, the resistances RE and R of the feedback circuit
When A, RB, etc. are externally connected, the external devices are connected to the resistor and IC section 2.
Since the resistance variations within the two terminals are different, the gain varies. On the other hand, in current IC manufacturing methods, it is difficult to control the absolute value of the resistance value, but it is easy to control the ratio (relative ratio) of the resistance value, so accurate gain can be obtained. .

Further, the IC section 2 has the same configuration whether it is dual connection or BTL connection, and the wiring can be operated externally.As explained above, according to the present invention, dual connection, In either case of BTL connection, it is possible to provide a power amplification IC that has little variation in gain and is easy to design, manufacture, etc.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams showing each embodiment of the present invention, and Figure 3 is a circuit diagram showing each embodiment of the present invention.
4 are circuit diagrams showing a conventional example. DESCRIPTION OF SYMBOLS 1... Input signal source, 2... IC part for power amplification, 3° 4... Amplifier (op-amp), 5... Load, 111
~119...External lead-out terminal, 12...Switch, R
A. RB r RE , RF , R9”'Resistance. Applicant's representative Patent attorney Takehiko Suzue

Claims (1)

[Claims] The resistors and amplifiers that determine the gain in BTL connection are formed in the same chip, and when dual connection is used, some of the resistors are left unused, and when BTL connection is made, the resistors are used. The power amplification IC is characterized in that switching between the dual connection and the BTL connection is performed by switching a switch or selectively using the presence or absence of wiring.