HFA3101BZ Intersil, HFA3101BZ Datasheet - Page 5

• Manufacturer Part Number: HFA3101BZ
• Description: IC TRANSISTOR ARRAY UHF 8-SOIC
• Manufacturer: Intersil

Specifications of HFA3101BZ

• Frequency: 0Hz ~ 10GHz
• Number Of Mixers: 1
• Noise Figure: 1.7dB
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Voltage - Supply: -
• Rf Type: -
• Gain: -
• Secondary Attributes: -

Application Information
The HFA3101 array is a very versatile RF Building block. It
has been carefully laid out to improve its matching
properties, bringing the distortion due to area mismatches,
thermal distribution, betas and ohmic resistances to a
minimum.
The cell is equivalent to two differential stages built as two
“variable transconductance multipliers” in parallel, with their
outputs cross coupled. This configuration is well known in
the industry as a Gilbert Cell which enables a four quadrant
multiplication operation.
Due to the input dynamic range restrictions for the input
levels at the upper quad transistors and lower tail transistors,
the HFA3101 cell has restricted use as a linear four quadrant
multiplier. However, its configuration is well suited for uses
where its linear response is limited to one of the inputs only,
as in modulators or mixer circuit applications. Examples of
these circuits are up converters, down converters, frequency
doublers and frequency/phase detectors.
Although linearization is still an issue for the lower pair input,
emitter degeneration can be used to improve the dynamic
range and consequent linearity. The HFA3101 has the lower
pair emitters brought to external pins for this purpose.
In modulators applications, the upper quad transistors are
used in a switching mode where the pairs Q
act as non saturating high speed switches. These switches
are controlled by the signal often referred as the carrier
input. The signal driving the lower pair Q
used as the modulating input. This signal can be linearly
transferred to the output by either the use of low signal levels
(Well below the thermal voltage of 26mV) or by the use of
emitter degeneration. The chopped waveform appearing at
the output of the upper pair (Q
that is multiplied by +1 or -1 at every half cycle of the
switching waveform.
+1
-1
FIGURE 1. TYPICAL MODULATOR SIGNALS
DIFFERENTIAL OUTPUT
MODULATING SIGNAL
CARRIER SIGNAL
3-5
1
to Q
4
) resembles a signal
5
/Q
1
6
/Q
is commonly
2
and Q
3
/Q
HFA3101
4
Figure 1 shows the typical input waveforms where the
frequency of the carrier is higher than the modulating signal.
The output waveform shows a typical suppressed carrier
output of an up converter or an AM signal generator.
Carrier suppression capability is a property of the well known
Balanced modulator in which the output must be zero when
one or the other input (carrier or modulating signal) is equal
to zero. however, at very high frequencies, high frequency
mismatches and AC offsets are always present and the
suppression capability is often degraded causing carrier and
modulating feedthrough to be present.
Being a frequency translation circuit, the balanced modulator
has the properties of translating the modulating frequency
(ω
bands ω
some translating schemes being used by balanced mixers.
FIGURE 2A. UP CONVERSION OR SUPPRESSED CARRIER AM
M
FIGURE 2C. ZERO IF OR DIRECT DOWN CONVERSION
) to the carrier frequency (ω
FIGURE 2. MODULATOR FREQUENCY SPECTRUM
U
= ω
C
FIGURE 2B. DOWN CONVERSION
ω
BASEBAND
C
+ ω
IF (
FOLDED BACK
- ω
ω
M
M
C -
and ω
ω
M )
L
ω
= ω
C
C
C
), generating the two side
ω
- ω
C
M
ω
. Figure 2 shows
C
+ ω
ω
ω
ω
M
M
C
M