Voltage multiplier circuit

Details Voltage multiplier circuit Voltage multiplier circuit

2001-12-17

2004-08-31

Choe, Henry (Department: 2817)

Amplifiers

With semiconductor amplifying device

Including differential amplifier

C330S253000

Reexamination Certificate

active

06784737

ABSTRACT:

FIELD
The present invention relates generally to amplifiers, and more specifically to amplifiers with programmable gain.
BACKGROUND
Amplifiers are commonly used to produce an output voltage or an output current in response to an input voltage or an input current. Voltage amplifiers receive an input voltage and produce an output voltage. Current amplifiers receive an input current and produce an output current. Other types of amplifiers also exist. For example, a transconductance amplifier receives an input voltage and produces an output current.
FIG. 1
shows a prior art amplifier circuit. Amplifier circuit
100
includes operational amplifier (op-amp)
102
, feedback resistor (R
f
)
104
, and input resistors (R
1
, R
2
)
106
and
108
. Amplifier circuit
100
produces an output voltage (V
OUT
) on node
110
from input voltages (V
IN1
, V
IN2
) on nodes
112
and
114
. The output voltage satisfies the following equation:
V
OUT
=
(
-
R
f
R
1
)
⁢
V
IN1
+
(
-
R
f
R
2
)
⁢
V
IN2
(
1
)
As shown in equation (1) above, amplifier circuit
100
scales (or “multiplies”) each input voltage by a constant value and sums the scaled voltage values. The constant values used to scale the input voltages are equal to a ratio of resistance values. By varying the resistance values of resistors
104
,
106
, and
108
, the input voltage scaling can be changed.
As is known in the art, amplifier circuit
100
has many uses. It is also known in the art that amplifier circuit cannot operate at extremely high frequencies, in part because op-amp
102
usually includes compensation circuits to avoid instability, and these compensation circuits tend to limit the frequency at which the op-amp can operate.
Other example circuits that provide voltage multiplication include the “Gilbert cell” as described in chapter eight of: David A Johns & Ken Martin, “Analog Integrated Circuit Design,” (1997).
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for methods and apparatus to provide amplifiers and multipliers that operate at high frequencies.


REFERENCES:
patent: 4459555 (1984-07-01), Jett, Jr.
patent: 4853610 (1989-08-01), Schade, Jr.
patent: 5455522 (1995-10-01), Jones
patent: 6597303 (2003-07-01), Cosand
IEEE, Ota extended adjustment range and linearization via programmable current mirrors.*
Comer, D.T., et al., “A CMOS Voltage to Current Converter For Low Voltage Applications”,This information is directly from Donald T. Comer's web site.http://www.ee.byu.edu/faculty/comerdt/publications.html, 13 p., (Feb. 11, 1997).
Farjad-Rad, R., et al., “A 0.4-um CMOS 10-Gb/s 4-PAM Pre-Emphasis Serial Link Transmitter”,IEEE Journal of Solid-State Circuits, 34 (5), pp. 580-585, (May 1999).

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