
Data Sheet ZL10100
3
SEMICMF.017
1.0 Functional Description
The ZL10100 is a bipolar, broadband wide dynamic range mixer oscillator with on-board I2C bus controlled PLL
frequency synthesiser, optimised for application as the down converter in double conversion tuner systems. It
also has application in any system where a wide dynamic range broadband synthesised frequency converter is
required.
The ZL10100 is a single chip solution containing all necessary active circuitry and simply requires an external
tuneable resonant network for the local oscillator sustaining network. The pin assignment is contained in the
the block diagram in Figure 1 and the Pin Description in Figure 2.
1.1 Converter section
In normal application the HIIF input is interfaced through appropriate impedance matching to the device input.
The RF input preamplifier of the device is designed for low noise figure, within the operating region of 1 to 1.3
GHz and for high intermodulation distortion intercept so offering good signal to noise plus composite distortion
spurious performance when loaded with a multi carrier system. The preamplifier also provides gain to the mixer
section and back isolation from the local oscillator section. The typical RF input impedance and matching
network for matching to a 1220 MHz HIIF filter, type B1603 are contained in Figures 3 and 4.
The output of the preamplifier is fed to the mixer section which is optimised for low radiation application. In this
stage the RF signal is mixed with the local oscillator frequency, which is generated by the on-board oscillator.
The oscillator block uses an external tuneable network and is optimised for low phase noise. The typical
application is shown in Figure 5, and the phase noise performance in Figure 6. This block interfaces direct with
the internal PLL to allow for frequency synthesis of the local oscillator.
The output of the mixer is internally coupled to a differential IF amplifier, which provides further gain and
provides for a 150 Ω, differential output impedance and drive capability. The IF amplifier allows for IF
frequencies between 30 and 60 MHz.
The typical IF output impedance is contained in Figure 7.
The typical key performance data at 5V Vcc and 25 deg C ambient are shown in the Quick Reference Data
section on Page 2.
1.2 Local Oscillator
To maximise the local oscillator phase noise performance, the application circuit as in Figure 5 must be
carefully adhered to including the component type and manufacture where applicable, strip line dimension and
board material. Any deviation from these parameters may adversely affect phase noise characteristics and so
will require re-optimisation.
1.3 PLL frequency Synthesiser
The PLL frequency synthesiser section contains all the elements necessary, with the exception of a reference
frequency source and loop filter to control the oscillator, so forming a complete PLL frequency synthesised
source. The device allows for operation with a high comparison frequency and is fabricated in high speed logic,
which enables the generation of a loop with good phase noise performance.
The LO signal from the oscillator drives an internal preamplifier, which provides gain and reverse isolation from
the divider signals. The output of the preamplifier interfaces direct with the 15-bit fully programmable divider.
The programmable divider is of MN+A architecture, where the dual modulus prescaler is 16/17, the A counter is
4-bits, and the M counter is 11 bits.
The output of the programmable divider is fed to the phase comparator where it is compared in both phase and
frequency domain with the comparison frequency. This frequency is derived either from the on-board crystal
controlled oscillator or from an external reference source. In both cases the reference frequency is divided
down to the comparison frequency by the reference divider which is programmable into 1 of 29 ratios as
detailed in Table 1. The typical application for the crystal oscillator is contained in Figure 8 which also
demonstrates how a 4 MHz reference signal can be coupled out to a further PLL frequency synthesiser, such as
the upconverter section in a double conversion tuner.